基于金属有机框架化合物设计制备高活性碳基纳米电催化剂

This proposal is aimed at designning and preparing highly active and inexpensive carbon-based electrocatalysts for both OER and HER by annealing of metal−organic frameworks (MOFs). A facile and universal strategy for synthesizing nonprecious transition metals, binary alloys, and ternary alloys encapsulated in graphene layers via direct annealing of MOFs will be investigated. The presence of carbon such as graphene would lead to the improvement of conductivity of electrocatalysts,while the electronic structure viriation due to the changing of coodination enviroment of activie sites may help to increase its activity by decreasing its free energy ΔGH*. Detail characterizations based on X-ray adsorption near edge structure (XANES) and Density functional theory calculations will be used to reveal the electronic structures of catalysts and catalytic mechanism. The project would help to find novel highly active catalysts and understand the electrocatalytic mechanism.

电化学催化剂可以降低反应的能垒，提高效率。寻找高效、稳定且易得的纳米催化剂成为近年来的热点和难点。本课题拟以金属有机框架化合物（MOFs）为前驱体来设计合成新型、高活性的碳基纳米电化学催化剂。拟通过控制MOFs前驱物的形貌和后续退火条件，来控制纳米催化剂的形貌（如空心、核壳、异质结等）；通过改变MOFs中金属离子（如过渡金属Co等）和有机配体的组成（含N、S、P等元素的有机配体）以及退火工艺来制备不同的碳基复合纳米催化剂（如类石墨烯与金属合金、硫化物、氮化物、磷化物、钙钛矿材料的复合，单原子掺杂碳材料等）。碳的复合能提高催化剂的导电性，活性位点配位环境的改变能调控其氢原子吸附自由能ΔGH*，藉此发现具有高本征催化活性的纳米电催化剂。通过X-射线吸收精细结构等表征和理论计算来揭示催化剂的高活性来源及催化反应机理，以指导催化剂的设计与合成。该项目的实施对制备新型、高效的电化学催化剂有重要意义。

课题基于 MOFs设计制备了一系列高效电催化剂，研究了催化的“构效关系”，取得了一批创新成果。如在石墨烯六元环里通过双石墨型N掺杂制备了高活性析氢催化剂。在N掺杂石墨烯基底上制备了五元环拓扑缺陷结构催化剂，理论和实验相结合研究了它们的电催化应用和催化机制。以含有金属Mn的MOFs作为前驱物，将O和N原子配位的Mn活性位点原子级地分散在三维石墨烯骨架中，利用石墨烯的良好导电性成功地将Mn调控成高活性的ORR催化活性位点，实现了高活性的催化。获授权国家发明专利2项；发表了16篇高水平研究论文, 完成了预期任务。